Archive for April 5, 2011

This has been a cold winter in North Pole, Alaska. (That’s a suburb of Fairbanks, by the way, not the North Pole.) It didn’t feel like a cold winter. I really expected it to be warmer than usual, mostly because we had so little weather with temperatures below -40 degrees F. (Or C, the two temperature scales cross at that point.) Instead, the period from Dec 1 to February 28 averaged 4 degrees F below normal. Why?

We don’t tend to remember events that are near normal. For us here in interior Alaska, winter temperatures aren’t perceived as all that cold until they reach 40 below. That’s when ice fog becomes a problem, tires become square and no longer grip the road, snow is like loose sand, and plastic shatters. Anything above around +20 in midwinter is a heat wave. Above freezing, we really worry–roads are usually ice covered, and they get very slippery when they thaw, even a little. We also tend to go more by daily high temperatures than by low in winter–anything that can freeze is frozen. (This obviously reverses during the growing season, but we’re talking winter here.)

The numbers differ according to where you live and how long you’ve lived there. I came to Alaska in the 60’s, and I remember all too well periods of several days with the daily high temperature being well below 40 below. (My old Master’s thesis records a five-day stretch of continuous 40 below, much of it 50 below or colder, and another that lasted 9 days.) That’s frigid! But we didn’t have any periods like that this year, so I didn’t perceive the winter as being particularly cold.

How about month by month? December was cold: -17.9 is 12 degrees F below normal. But there was very little extreme weather, in either direction. No high temperatures outside the +20 to -40 range, and only four days when the overnight low dropped to or below -40. Average, on extremes, or perhaps less extreme than normal. But it was also true that every single day had a low temperature below 0 F, and all but four days had daily high temperatures below 0. (That average, by the way, is obtained by adding up all the daily highs and lows and dividing them by twice the number of days in the month.)

January was quite a bit warmer by the official record. The average monthly temperature was – 6.0 degrees F, 3.7 degrees above normal. I would have said about the same as December except for the warm spell at the beginning of the month. But that warm spell, with two daily highs above freezing and five above 20, was enough to offset the three days of -40 or colder lows later in the month. We also had quite a few more days with daily highs above 0 — 19, in fact. So it did feel a little warmer than December, but not all that much. Again, the really cold weather was lacking.

February had an average monthly temperature of -6.5, 2.7 degrees below normal. It felt warmer than that, probably because the sun was back. But we still had only 5 days with temperatures at or above +20 F, and 3 days with lows below -40 F — colder than any of those in December and January, in fact. But the lack of really extreme low temperatures made February and the winter as a whole seem warmer than it was.

Official temperatures often don’t match what we remember, simply because what we remember tends to be the really extreme weather. It’s not that the weather service records are inaccurate, it’s just the way they are put together to make averages. It’s not the way we remember things.

How did the “official” temperatures compare with the way you remember the winter where you live?